In recent years, a large number of various machining centers have been developed for finishing both large and small series of complicated workpieces. The tool magazines of these machining centers can potentially contain a larger number of tools. The large storage capacity of the tool magazine makes possible a correspondingly large number of various finishing procedures for the same or different workpieces, without requiring manual intervention in the finishing process. However, the capital investment required for these complex machining centers and the amount of space they themselves (and especially their magazines) take up, have proven disadvantageous. Although electronically-driven universal cutting and drilling machining tools--suited for automatic finishing of even complex workpieces on account of their fixed chain drives and digital control mechanisms--have become known, the number of single, independently running finishing operations which can be accomplished with these machine tools has been limited by the reduced capacity of their tool magazines. An increase in the intake capacity of the tool magazine would result in both increased capital expenditures and an increase in the overall size of the machine tool.
German patent publication No. 36 07 391 describes a tool trolley for transporting a tool magazine among analog-driven machine tools. The tool trolley, which can also fulfill the function of an auxiliary magazine, features both a tool storage area in the form of a revolving chain with tool uptake points, and a tool exchanger with movable tongs for transporting a selected tool back and forth between the tool storage unit to the machine's tool magazine. A horizontally and vertically adjustable carriage, which bears the tool storage area on its vertical outer side and the tool exchanger on its horizontal upper side, is located on the plate-shaped trolley carrier. The tool exchanger features a support which adjusts horizontally and diagonally relative to the carriage, as well as an elbow joint carrier which can be revolved along a diagonal axis and which features two diametrically opposed grip arms with tongs mounted on them. Although this well-known tool trolley can also be used as an auxiliary magazine, it was developed primarily for the transport of several finishing machines together with their tools. From the point of view of construction, the aforementioned tool trolley is rendered wasteful by, among other things, the various aggregate drives and the way in which they are controlled.
German patent publication No. 33 31 293 describes a tool exchange construction setup for a machining tool, which features a revolving plate-shaped main magazine with a large number of tool cartridges and, next to the main magazine, a revolving plate-shaped auxiliary magazine mounted on a trolley. With the help of thrust cylinders, the cartridges containing the tools are transported back and forth from the main magazine into empty spaces of the auxiliary magazine. This familiar setup is also technologically wasteful and possesses only a limited storage capacity.